The #17A(R)S has the same mounting platform as the #17A(R), measures 1 9/16a ^2 and was developed for small pocket scopes and laser attachments. The standard STANAG width channel allows secure laser or night vision optic attachment at two points. The New MK-II LeverA(R) features a built-in precision adjustment wheel allowing finger tip (no tool) selection to desired tension to fit variations in 1913 Mil-Std Dimensions. The mounts adjustment wheel comes pre-gauged and locked to the center of the Mil-Std dovetail specs. The hash marks to the left or right of the adjustment wheels white marked indicator line, represent .002 US Pat. No. 5276988, 7493721, D57344 100% M Mfg: A.R.M.S.